This invention relates to pharmacology. More specifically, the invention relates to compositions of matter useful for preparing medicaments for the treatment of various disorders.
A number of chronic disorders have symptoms which are known to be very difficult to treat, and often fail to respond to safe, non-addictive, and non-steroid medications. Such disorders, such as intractable coughing, fail to respond to conventional medicines and must be treated by such drugs as codeine, morphine, or the anti-inflammatory steroid prednisone. These drugs are unacceptable for long-term treatment due to dangerous side-effects, long-term risks to the patient""s health, or the danger of addiction. Other disorders, such as dermatitis, have no satisfactory treatment for the severe itching and rash at this time. Drugs such as prednisone and even tricyclic antidepressants, as well as topical applications, have been tried, but do not appear to offer substantial and consistent relief.
Chronic pain due to conditions such as stroke, cancer, trauma, as well as neuropathic pain resulting from conditions such as diabetes and shingles (herpes zoster), for example, is also a problem which resists treatment. Chronic pain is estimated to affect millions of people. A variety of therapies for this type of pain have been tried, but there remains a need for safe and effective treatments.
The compound dextromethorphan, or (+)-3-methoxy-N-methylmorphinan, has been used as a cough suppressant ingredient in cough syrups. Dextromethorphan has also been tested as a potential therapeutic agent for stroke, and progressive neurodegenerative diseases such as Parkinson""s disease, Alzheimer""s disease and amyotrophic lateral sclerosis. However, the effectiveness of dextromethorphan for the treatment of any disorder has been limited because it is rapidly broken down by the liver and excreted in most individuals.
It is an object of the present invention to provide a combination of compounds useful for the preparation of medicaments which will effectively treat formerly intractable conditions not responsive to other medications. It is also an object of the present invention to provide medicaments which are safe, non-addictive, and relatively free of side-effects for patients suffering from long-term intractable conditions.
The present invention provides compounds which are useful in the preparation of medicaments for the treatment of a variety of disorders including intractable coughing, dermatitis, chronic pain, tinnitus and sexual dysfunction. These compounds are a therapeutically effective dosage of dextromethorphan and a therapeutically effective dosage of a second agent, an inhibitor of enzymatic dextromethorphan oxidation. This combination of compounds can be administered together, or individually. A preferred combination is dextromethorphan and the oxidative inhibitor quinidine. Inhibitors which may also be used include quinine, yohimbine, fluoxetine, haloperidol, ajmaline, lobeline, and pipamperone.